Data converters play a crucial rule in the electronics field as they bridge the analog world to the digital domain and vice versa in modern integrated circuits (ICs). Over the last decades, significant progress has been achieved in designing high resolution analog-to-digital converters (ADCs) and digital-to-analog converters (DACs). In order to characterize such sophisticated data converters, especially ADCs, spectral testing is now widely utilized. The spectral testing normally requires an analog input signal to the tested ADC having 3 to 4 bits more purity than the tested ADC itself. If the analog input signal does not meet the high purity requirement, the ADC output spectrum will no longer contain just ADC nonlinearity, but will also contain nonlinearity from the analog input signal. The ADC's specifications, such as total harmonic distortion (THD) and spurious free dynamic range (SFDR), cannot be accurately obtained from the output spectrum.
In some applications, the analog input signal for the tested ADC may be generated by a high purity DAC with superior linearization. However, when the resolution of the tested ADC is high, for instance a 16-bit, it is very challenging (sophisticated circuitry design, and or complicated calibration) and costly to design a high purity DAC with superior linearization to achieve a pure enough analog input signal.
Accordingly, there remains a need for an improved DAC linearization system that provides ultra-pure sinusoidal/cosinusoidal signals with an easy implementation at a low cost.